检索结果-南通市图书馆

Exploration of the Existence Forms and Patterns of Dissolved Oxygen Molecules in Water

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第10期16卷 337-349页

作者： Hewei Yuan Yaozhong zhang Xiaolu Huang Xiwu zhang Jinjin Li Yufeng Huang Kun Li Haotian Weng Yang Xu yafei zhang Key Laboratory of Thin Film and Microfabrication(Ministry of Education) Department of Micro/Nano ElectronicsSchool of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240People's Republic of China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240People's Republic of China Jinduo Yuchen Water Environment Engineering Co. LtdShanghai 201702People's Republic of China

The structure of liquid water is primarily composed of three-dimensional networks of water clusters formed by hydrogen bonds,and dis-solved oxygen is one of the most important indicators for assessing water *** this work,distilled water with different concentration of dissolved oxygen were prepared,and a clear negative correlation between the size of water clus-ters and dissolved oxygen concentration was ***,a phenomenon of rapid absorption and release of oxygen at the water interfaces was unveiled,suggesting that oxygen molecules predominantly exist at the interfaces of water *** molecules can move rapidly through the interfaces among water clusters,allowing dissolved oxygen to quickly reach a saturation level at certain partial pressure of oxygen and *** exploration into the mechanism by molecular dynamics simulations of oxygen and water clusters found that oxygen molecules can only exist stably at the interfaces among water clusters.A semi-empirical formula relating the average number of water molecules in a cluster(n)to ^(17)O NMR half-peak width(W)was summarized:n=0.1 W+*** findings provide a foundation for exploring the structure and properties of water.

关键词： Water clusters Dissolved oxygen ^(17)O NMR Molecular dynamics simulation

Dynamic failure process of expanded polystyrene particle lightweight soil under cyclic loading using discrete element method

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第4期23卷 815-828页

作者： Zhou, Wei Hou, Tianshun Chen, Ye Wang, Qi Luo, Yasheng zhang, yafei College of Water Resources and Architectural Engineering Northwest A&F University Xianyang China Xi’an Key Laboratory of Geotechnical and Underground Engineering Xi’an University of Science and Technology Xi’an China Hanjiang to Weihe River Valley Water Diversion Project Construction Co. Ltd. Xi’an China

Expanded polystyrene (EPS) particle-based lightweight soil, which is a type of lightweight filler, is mainly used in road engineering. The stability of subgrades under dynamic loading is attracting increased research attention. The traditional method for studying the dynamic strength characteristics of soils is dynamic triaxial testing, and the discrete element simulation of lightweight soils under cyclic load has rarely been considered. To study the meso-mechanisms of the dynamic failure processes of EPS particle lightweight soils, a discrete element numerical model is established using the particle flow code (PFC) software. The contact force, displacement field, and velocity field of lightweight soil under different cumulative compressive strains are studied. The results show that the hysteresis curves of lightweight soil present characteristics of strain accumulation, which reflect the cyclic effects of the dynamic load. When the confining pressure increases, the contact force of the particles also increases. The confining pressure can restrain the motion of the particle system and increase the dynamic strength of the sample. When the confining pressure is held constant, an increase in compressive strain causes minimal change in the contact force between soil particles. However, the contact force between the EPS particles decreases, and their displacement direction points vertically toward the center of the sample. Under an increase in compressive strain, the velocity direction of the particle system changes from a random distribution and points vertically toward the center of the sample. When the compressive strain is 5%, the number of particles deflected in the particle velocity direction increases significantly, and the cumulative rate of deformation in the lightweight soil accelerates. Therefore, it is feasible to use 5% compressive strain as the dynamic strength standard for lightweight soil. Discrete element methods provide a new approach toward the dynamic

关键词： lightweight soil cyclic loading dynamic triaxial test discrete element method hysteresis curve

On the Normalized Laplacian Spectral Radius of Traceable Graphs

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mathematical Research with Applications 2024年第3期44卷 291-303页

作者： yafei zhang Fei WEN Yonglei CHEN Institute of Applied Mathematics Lanzhou Jiaotong University

In this paper, we give some sufficient conditions for a graph to be traceable in terms of its order and size. As applications, the normalized Laplacian spectral conditions for a graph to be traceable are established.

关键词： traceable graphs normalized Laplacian spectral radius degree sequence

Dynamic failure process of expanded polystyrene particle lightweight soil under cyclic loading using discrete element method

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第04期 815-828页

作者： Zhou Wei Hou Tianshun Chen Ye Wang Qi Luo Yasheng zhang yafei College of Water Resources and Architectural Engineering Northwest A&F University Xi'an Key Laboratory of Geotechnical and Underground Engineering Xi'an University of Science and Technology Hanjiang to Weihe River Valley Water Diversion Project Construction Co. Ltd.

Expanded polystyrene(EPS) particle-based lightweight soil, which is a type of lightweight filler, is mainly used in road engineering. The stability of subgrades under dynamic loading is attracting increased research attention. The traditional method for studying the dynamic strength characteristics of soils is dynamic triaxial testing, and the discrete element simulation of lightweight soils under cyclic load has rarely been considered. To study the meso-mechanisms of the dynamic failure processes of EPS particle lightweight soils, a discrete element numerical model is established using the particle flow code(PFC) software. The contact force, displacement field, and velocity field of lightweight soil under different cumulative compressive strains are studied. The results show that the hysteresis curves of lightweight soil present characteristics of strain accumulation, which reflect the cyclic effects of the dynamic load. When the confining pressure increases, the contact force of the particles also increases. The confining pressure can restrain the motion of the particle system and increase the dynamic strength of the sample. When the confining pressure is held constant, an increase in compressive strain causes minimal change in the contact force between soil particles. However, the contact force between the EPS particles decreases, and their displacement direction points vertically toward the center of the sample. Under an increase in compressive strain, the velocity direction of the particle system changes from a random distribution and points vertically toward the center of the sample. When the compressive strain is 5%, the number of particles deflected in the particle velocity direction increases significantly, and the cumulative rate of deformation in the lightweight soil accelerates. Therefore, it is feasible to use 5% compressive strain as the dynamic strength standard for lightweight soil. Discrete element methods provide a new approach toward the dynamic p

关键词：

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

人口老龄化、数字经济与就业技能结构

中国人口·资源与环境 2024年第7期34卷 170-183页

作者：肖周燕张亚飞首都经济贸易大学劳动经济学院北京100070

人口老龄化和数字经济是影响社会经济发展的两大因素,有必要探讨这两种因素如何相互作用并影响劳动力市场。该研究以数字经济为视角,基于两阶段世代交叠模型,将人口老龄化、数字经济与就业结构放在同一框架进行理论分析,在此基础上构建... 详细信息

人口老龄化和数字经济是影响社会经济发展的两大因素,有必要探讨这两种因素如何相互作用并影响劳动力市场。该研究以数字经济为视角,基于两阶段世代交叠模型,将人口老龄化、数字经济与就业结构放在同一框架进行理论分析,在此基础上构建中国2010—2019年279个地级及以上城市的面板数据,利用双向固定效应模型和门槛模型,检验了人口老龄化对就业技能结构的影响,并进一步探讨数字经济在老龄化对就业结构影响中的调节作用。研究发现:①人口老龄化增加了低技能行业就业,减少了中、高技能行业就业,导致就业技能结构呈低技能行业偏向的单极化趋势。②数字经济强化了老龄化增加中、低行业就业的积极作用,弱化了老龄化减少高技能行业就业的消极作用,使得就业技能结构由低技能行业的单极化向高、低技能行业两极化转变。③随着数字经济发展加快,人口老龄化最先影响低技能行业就业,中等技能行业就业次之,高技能行业就业受影响最晚。④数字经济主要通过人力资本提升和产业升级调节老龄化对就业技能结构的影响。⑤异质性分析表明,数字经济减缓了老龄化对就业技能结构冲击。因此,建议地方政府结合人口老龄化产业发展方向以及消费需求特色,合理规划数字经济发展道路,充分发挥数字经济带来的发展新动力,推动数字经济与老龄化融合发展,减轻人口老龄化对就业结构的负向冲击。同时,制定并完善“三孩政策”相应的托育保障,大力发展普惠托育服务,减缓人口老龄化的深化速度,促进人口长期均衡发展。

关键词：数字经济人口老龄化就业结构

维普期刊数据库博看期刊

同方期刊数据库

面向高动态范围成像的内容恢复和鬼影抑制网络

在线全文

学校读者我要写书评

暂无评论

模式识别与人工智能 2024年第4期37卷 313-327页

作者：杨珍妹李华锋张亚飞昆明理工大学信息工程与自动化学院昆明650504

基于多曝光融合的高动态范围(High Dynamic Range,HDR)成像旨在整合多幅低动态范围图像(Low Dynamic Range,LDR)的信息,以生成高质量的HDR图像.然而,抑制运动区域的鬼影信息和恢复过饱和区域的缺失信息仍是HDR成像面临的两大挑战.为了... 详细信息

基于多曝光融合的高动态范围(High Dynamic Range,HDR)成像旨在整合多幅低动态范围图像(Low Dynamic Range,LDR)的信息,以生成高质量的HDR图像.然而,抑制运动区域的鬼影信息和恢复过饱和区域的缺失信息仍是HDR成像面临的两大挑战.为了综合考虑对参考图像缺失内容的恢复和运动区域鬼影的抑制,文中提出面向HDR成像的内容恢复和鬼影抑制网络.在内容恢复方面,引入基于预测滤波的内容恢复块.由内容恢复块预测到的滤波核对参考图像特征进行滤波,整合参考图像和非参考图像中的关键信息,为有效进行缺失内容的重建提供更丰富的信息.为了抑制运动区域的鬼影信息并充分利用非参考图像中的互补信息,引入可变形卷积,将非参考图像特征与参考图像特征对齐.此外,为了提升网络的HDR图像重建能力,构建三支路图像重建模块,包括一条主支路和两条辅助支路,辅助支路协助主支路在HDR结果的生成过程中更好地保留细节.实验表明,文中网络在主观视觉和客观指标上均具有较优表现.

关键词：高动态范围成像鬼影抑制预测滤波内容恢复

在线全文

学校读者我要写书评

暂无评论

足踝复合体本体感觉的测量与评价

中国组织工程研究 2024年第20期28卷 3259-3264页

作者：冯亮张雅飞霍洪峰河北师范大学体育学院河北省石家庄市050024 河北医科大学临床学院河北省石家庄市050017 河北省人体运动生物信息测评重点实验室河北省石家庄市050024

背景:足踝本体感觉的研究对于慢性踝关节不稳、老年疾病的康复治疗以及身体姿势控制、运动表现的提高至关重要。前期的相关研究经常把足部和踝关节的感觉评价分开研究,对全面且综合地了解其感觉功能存在一定的局限。目的:足踝复合体是... 详细信息

背景:足踝本体感觉的研究对于慢性踝关节不稳、老年疾病的康复治疗以及身体姿势控制、运动表现的提高至关重要。前期的相关研究经常把足部和踝关节的感觉评价分开研究,对全面且综合地了解其感觉功能存在一定的局限。目的:足踝复合体是唯一与支撑面直接接触的部位,在收集体感反馈和调节平衡控制中起重要作用。文章通过汇总现有关于足部和踝关节本体感觉的调查研究,梳理足踝复合体感觉的测量与评价方法,以期为日后的相关研究做出铺垫并提供理论依据。方法:中文检索词为“(足OR足踝关节OR踝关节)AND(感觉OR本体感觉)”、英文检索词为“(foot OR ankle)AND(feel OR proprioception)”,在Web of Science、PubMed和中国知网数据库检索相关文献,了解关于足踝基本概念、研究现状与范畴,总结并评价足踝的本体感觉评价方法,最终纳入57篇文献进行综述分析。结果与结论:①足踝复合体感觉的评价主要分为对足部的感觉评价和踝关节的本体感觉评价。②足部的感觉评价主要描述其皮肤的感觉以及干预条件下的感觉反馈,方法主要包括:压力感觉阈值测试、足(底侧和跖侧)两点辨别能力测试、皮肤振动感觉持续时间测试。③踝关节本体感觉评价着重描述关节位置、运动范围、力值及功能表现,方法主要分为静态的关节角度重置测试、运动最小阈值测试、力觉重现测试以及动静态的平衡、速度及行走能力的测试。④对量化结果的报道一般以“误差”来表示,根据报道的需要一般分为:绝对误差、相对误差和恒定误差等。⑤结果证实,足踝复合体具备特殊的感觉能力,包括足部感觉和踝关节的本体感觉,影响人类的生活质量以及运动表现;足部感觉与踝关节本体感觉的弱化均与人体平衡能力下降相关,二者联合测量可以全面有效地评价足踝功能;根据不同的研究需求,需要选择足部与踝关节的感觉测量方法的组合形式,并充分考虑环境、情绪以及报道方式等多种影响因素,提高测量与评价的有效性。

关键词：足踝复合体本体感觉测量方法等速测试仪感觉阈值两点辨别能力皮肤振动感觉运动觉位置觉力量觉

基于层次分析灰色定权聚类的煤层气开发甜点预测方法——以柿庄北区块为例

在线全文

学校读者我要写书评

暂无评论

煤炭科学技术 2024年第5期52卷 166-175页

作者：张亚飞张松航邓志宇王瑞欣刘广景中联煤层气有限责任公司北京100016 中国地质大学(北京) 北京100083

随着煤层气产业的发展以及非常规油气勘探开发一体化的要求,当前煤层气的勘查评价工作逐渐由勘探选区向开发甜点选区推进。然而,受限于勘探开发阶段或资料占有程度,当前多数的选区评价体系对煤储层的可改性和煤层气的可采性考虑不足,在... 详细信息

随着煤层气产业的发展以及非常规油气勘探开发一体化的要求,当前煤层气的勘查评价工作逐渐由勘探选区向开发甜点选区推进。然而,受限于勘探开发阶段或资料占有程度,当前多数的选区评价体系对煤储层的可改性和煤层气的可采性考虑不足,在指导开发区井位优选或加密井方面效果不佳。基于沁水盆地柿庄北区块100余口煤层气参数井和开发井资料,分析区内3号煤层煤层气开发的资源条件、储层可改造性和煤层气可采性,采用层次分析和灰色定权聚类方法构建评价模型,评价了煤层气开发甜点区,为区内新井和加密井的部署提供依据。评价模型以煤层含气量、煤厚反映煤层气资源条件;综合考虑地应力环境和岩石力学性质,构建储层综合可改造性参数,评价储层可改造性;使用原始结构煤和碎裂煤占比、临储比和储层原始渗透率反映煤层气的可采性。每个参数采用word聚类方法分级,每个点位(每口井)计算出综合优度并排序,最终划分出煤层气开发甜点区。评价结果表明,研究区中部综合优度大于65的地区为进一步开展开发工作的甜点区。

关键词：煤层气柿庄北区块评价体系层次分析法灰色定权聚类开发甜点

基于变前视距离的四轮同步转向农机改进纯跟踪控制

在线全文

学校读者我要写书评

暂无评论

农业机械学报 2024年第3期55卷 21-28页

作者：沈跃赵莎张亚飞何思伟冯瑞刘慧江苏大学电气信息工程学院镇江212013

路径跟踪控制是提高自主导航系统控制精度的关键。针对在复杂农田作业环境下转弯时纯跟踪算法跟踪精度不高的问题,本文提出了一种基于改进纯追踪模型的四轮同步转向农机路径跟踪控制算法。建立了基于四轮同步转向农机的运动学模型和纯... 详细信息

路径跟踪控制是提高自主导航系统控制精度的关键。针对在复杂农田作业环境下转弯时纯跟踪算法跟踪精度不高的问题,本文提出了一种基于改进纯追踪模型的四轮同步转向农机路径跟踪控制算法。建立了基于四轮同步转向农机的运动学模型和纯跟踪模型,在此基础上考虑航向误差得到改进纯跟踪模型,进行RTK定位坐标修正,根据量化误差的评价函数搜索前视区域最优目标点,得到最优前视距离。本文算法能实时确定四轮同步转向农机改进纯跟踪模型中的前视距离,使航向误差和横向误差最小化,实现目标点的自适应优化。仿真结果表明,本文方法转弯时平均绝对横向误差减至0.035 m,平均绝对航向误差减至0.212°;水田实验结果表明,当四轮同步转向农机作业速度为3.6 km/h时,四轮转向农机轨迹跟踪平均绝对横向误差减至0.109 m,平均绝对航向误差减至2.799°,转弯跟踪精度显著提高。

关键词：水田四轮同步转向改进纯追踪控制前视距离自适应优化

维普期刊数据库博看期刊